1. Field of the Invention
This invention relates to fencing and more particularly to snow and sand fencing.
2. Description of the Prior Art
Snow fencing has existed for at least the past century and is designed primarily to either prevent or encourage drifting. In prevention embodiments, snow is allowed to build up on the windward side of the fence so as to eliminate drifting on the downwind side. In encouragement situations the fence is designed to provide an airflow flow downstream of the fence face in the direction of the prevailing wind which will cause snow to separate from the airstream downstream to build a drift. This invention is directed to the latter type of snow fence. The term snow fence, as used herein, is to be understood to be generic and include both snow and sand fencing of the type which is designed to cause deposit of the particulate, snow or sand, downstream of the fence in the direction of the prevailing wind.
Over the years many different types of snow fence have been suggested from the earliest rigid wooden solid fence to more recently developed roll fencing which utilizes vertical spaced wooden slats interwoven in a chain link or wire mesh fence. All such prior art devices have experienced considerable difficulties which are attributable to varying factors including:
(1) inability of the materials to withstand high winds; PA1 (2) inability of the materials to withstand harmonics created by winds; PA1 (3) inability of the materials to withstand environmental degradation over an accepted life span; PA1 (4) transportability; PA1 (5) difficulties of erection and disassembly; PA1 (6) ineffectiveness in depositing of particulate matter downwind of the fence; PA1 (7) susceptiblity to choking by deposit of particulate member upwind of the fence resulting in burying of the fence; and, PA1 (8) expense.
Originally snow fences were installed vertically, however, it has been known to use angle fences that have vertical portions adjacent the bottom and forward angled portions adjacent the top where the top portion was angled toward the prevailing wind. It has also been known to use rigid framing members framing individual sections of fence so that upon dismantling the snow fence at the end of the season the individual frame members could be stacked. More recently, it has been suggested to use plastics material in the construction of the fence for its light weight qualities, portability and stackability. However, most plastics suggested heretofore have proved to have unacceptably short life spans due to plastic elongation, sag, brittleness or inability to withstand heat.
Other difficulties encountered in snow fencing have included the failure to provide adequate hold down systems to maintain the snow fence in position during high wind condition while allowing the snow fence to be quickly erected and disassembled and, further, providing for movability of the fence during extreme cold weather without the necessity of substantial disassembly.
It would therefore be a considerable advance in the art to provide improved fence designs and constructions capable of overcoming the disadvantages of prior art design.